The 'Squared Circle' is the name given to a type of postmark which
originated in England in 1879.

It was an experimental design consisting of a circle, containing the
time and date of posting with also the name of the Post Office inscribed.This circle then had a series of corner bars and a triangle placed
at each corner so that the overall impression was that of a circle inserted
into a square, hence the name.

The idea of the Post Office was to design a single obliterator instead of
the previous type which consisted of two parts: one giving the place
and date information and a second one for heavily canceling the postage stamp
so that it could not be used again. This type was called a
"duplex obliterator."

The new design was immensely popular with Post Offices throughout
England and Wales to which they were supplied although none was ever issued
to Scotland nor to Ireland.

Do you have a Squared Circle Postmark? - You can check its rarity (Or RF)
by obtaining a copy of StanleyCohen's
Book Collecting British Squared Circle Postmarks!

Collecting British
Squared Circle Postmarks
by Stanley F. Cohen

The book gives lists of every Post Office that was issued with this
design from London to the provinces in great depth and sets out to explain
how these devices (called hammers) eventually became very worn through use
and how the Post Office, to save the expense of having new ones made, simply
'recut' the old ones until they themselves became worn out so that they were
recut again, often many times.

This particular type of postmark is one of many different types in
use that are collectable. However, until 1987 there was no handbook available
that comprehensively covered this fascinating field, which has become
tremendously popular with collectors since the publication of Stanley
Cohen's book. The book gives Rarity Factors for all the different offices, some of
which are so rare that only one copy has been found. Such rarities are
referred to as 'lonely greats'. Others are commonly found and the collector can study their
sometimes complex and sophisticated development and usage.

Stanley Cohen's work provides a great detail of information,
including many illustrations, with many features of these fascinating postmarks and explains how the Post
Office was able to distinguish between very similar looking hammers that
were issued to the larger offices in all kinds of subtle ways by 'numbering'
them. It explains how the Post Office changed its method of showing the time
posted, which, firstly, was a closely guarded secret until more modern times
when the correct time ("Clear Time") is shown.This book has received much recognition including the Philatelic Book of the Year Award, as it
contains so much vital and new information that it greatly assists not only
Squared Circle collectors but also collectors of other types of postmarks,
like Duplex ones, etc.